Variable displacement type swash plate compressor

ABSTRACT

A variable displacement type swash plate compressor includes a housing having therein a swash plate chamber and a plurality of cylinder bores, a drive shaft, a swash plate, a link mechanism, and a plurality of the pistons. The compressor further includes a partition member, a movable member, and a control pressure chamber, and a control mechanism. First and second seal members are disposed between the partition member and the movable member and between the drive shaft and the movable member, respectively, and are elastically deformed to provide sealing between the control pressure chamber and the swash plate chamber. At least one of a clearance formed between the partition member and the movable member and a clearance formed between the drive shaft and the movable member when the swash plate is at its minimum inclination angle is greater than when the swash plate at a maximum inclination angle position.

BACKGROUND OF THE INVENTION

The present invention relates to a variable displacement type swash plate compressor.

Japanese Patent Application Publication H05-172052 discloses a variable displacement type swash plate compressor (hereinafter simply referred to as compressor) which is shown in FIGS. 1 and 3. The compressor includes a housing, a drive shaft, a swash plate, a link mechanism, a plurality of pistons, a movable member and a control pressure chamber and a control mechanism. The housing has therein a plurality of cylinder bores, a swash plate chamber and a pressure control chamber. The housing further has therein a center hole that is connected to the swash plate chamber and the pressure control chamber.

The drive shaft is rotatably supported in the housing. The swash plate is rotatable with the rotation of the drive shaft in the swash plate chamber. The link mechanism is disposed between the drive shaft and the swash plate and permits changing of an inclination angle of the swash plate relative to an imaginary plane extending perpendicularly to the axis of the drive shaft. Each piston is reciprocally movably received in the cylinder bore so as to form a compression chamber therewith. A pair of shoes, which serves as part of a conversion mechanism, is disposed between each piston and the swash plate. With the rotation of the swash plate, the piston is caused to move reciprocally in the cylinder bore with a piston stroke length that is determined in accordance with the inclination of the swash plate.

The movable member is mounted on the drive shaft in the center hole of the housing. The movable member is axially slidably movable in the center hole so as to change the inclination angle of the swash plate. The movable member partitions between the pressure control chamber and the swash plate chamber. The movable member includes a seal member. The seal member is elastically deformed between the outer peripheral surface of the movable member and the inner peripheral surface of the center hole so as to seal therebetween. The control mechanism controls the pressure in the control pressure chamber.

In this compressor, when the pressure in the control pressure chamber is increased by the control mechanism, the movable member is slidably moved in the axial direction of the drive shaft towards the front housing in the axial hole, so that the inclination angle of the swash plate is increased through the link mechanism. Accordingly, the discharge volume per rotation of the drive shaft and hence the displacement of the compressor is increased. When the pressure in the control pressure chamber is reduced by the control mechanism, on the other hand, the movable member is slidably moved in the axial direction of the drive shaft toward the rear housing in the axial hole, so that the inclination angle of the swash plate is reduced through the link mechanism. Accordingly, the discharge volume per rotation of the drive shaft and hence the displacement of the compressor is reduced.

In the above-described compressor, the sliding movement of the movable member causes the seal member to be elastically deformed between the outer peripheral surface of the movable member and the inner peripheral surface of the axial hole while being moved axially. In increasing the displacement of the compressor by increasing the inclination angle of the swash plate, the pressure in the control pressure chamber acting on the movable member to slide axially need be increased enough to overcome the slide resistance of the seal member acting against the movement of the movable member. When the pressure in the control pressure chamber is decreased, the resistance of the seal member acting on the movable member becomes large for the pressure in the control pressure chamber acting on the movable member. Such resistance makes difficult the sliding movement of the movable member thereby to cause difficulty in increasing the inclination angle of the swash plate and hence the displacement of the compressor. Therefore, controlling the displacement of the compressor may become complicated.

The present invention, which has been made in light of the above-described problems, is directed to providing a variable displacement type swash plate compressor that permits precise controlling of the displacement of the compressor

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, there is provided a variable displacement type swash plate compressor including a housing having therein a swash plate chamber and a plurality of cylinder bores, a drive shaft rotatably supported in the housing, a swash plate mounted on the drive shaft for rotation therewith in the swash plate chamber, a link mechanism permitting changing of an inclination angle of the swash plate with respect to the an imaginary plane extending perpendicular to a direction of an axis of the drive shaft, and a plurality of the pistons received in the respective cylinder bores and connected to the swash plate, the pistons being reciprocally movable with the rotation of the drive shaft with a stroke length that is determined by the inclination angle of the swash plate. The compressor further includes a partition member mounted on the drive shaft for rotation therewith in the swash plate chamber, a movable member mounted on the drive shaft for rotation therewith in the swash plate chamber, and a control pressure chamber formed between the partition member and the movable member. The movable member is movable in the direction of the axis along with the drive shaft and the partition member to change the inclination angle. The control pressure chamber moves the movable member in the direction that increases the inclination angle with an increase of a pressure in the control chamber. The compressor further includes a control mechanism controlling the pressure in the control chamber. A first seal member is disposed between the partition member and the movable member and elastically deformed to provide sealing between the control pressure chamber and the swash plate chamber. A second seal member is disposed between the drive shaft and the movable member and is elastically deformed to provide sealing between the control pressure chamber and the swash plate chamber. A clearance formed between the partition member and the movable member when the swash plate is at a minimum inclination angle is greater than the clearance formed between the partition member and the movable member when the swash plate is at a maximum inclination angle position and/or a clearance formed between the drive shaft and the movable member when the swash plate is at the minimum inclination angle is greater than the clearance formed between the drive shaft and the movable member when the swash plate is at the maximum inclination angle.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of a compressor according to a first embodiment of the present invention, showing a state of the compressor with the swash plate at its minimum inclination angle position;

FIG. 2 is a longitudinal sectional view of the compressor of FIG.1, showing a state of the compressor with the swash plate at its maximum inclination angle position;

FIG. 3 is a schematic diagram of a control mechanism of the compressor of FIG.1;

FIG. 4 is an enlarged fragmentary cross-sectional view of the compressor of FIG. 1, showing a drive shaft, a partition member, a movable member and a control pressure chamber;

FIG. 5 is an enlarged fragmentary cross-sectional view of the compressor of FIG. 1, showing a clearance between the partition member and the movable member when the inclination angle is large;

FIG. 6 is an enlarged fragmentary cross-sectional view of the compressor of FIG. 1, showing a clearance between the partition member and the movable member when the inclination angle is small;

FIG. 7 is an enlarged fragmentary cross-sectional view of a compressor according to a comparison example, showing a drive shaft, a partition member, a movable member and a control pressure chamber;

FIG. 8 is a chart showing a change of pressure in the control pressure chamber acting on the movable member and changes of resistance of O-rings acting on the movable member in the compressor of FIG. 7;

FIG. 9 is a chart showing a change of pressure in the control pressure chamber acting on the movable member and changes of resistance of O-rings acting on the movable member in the compressor of FIG. 1;

FIG. 10 is an enlarged fragmentary cross-sectional view of a compressor according to a second embodiment of the present invention, showing a drive shaft, a partition member, a movable member and a control pressure chamber;

FIG. 11 is an enlarged fragmentary cross-sectional view of a compressor according to a third embodiment of the present invention, showing a drive shaft, a partition member, a movable member and a control pressure chamber;

FIG. 12 is an enlarged fragmentary cross-sectional view of a compressor according to a fourth embodiment of the present invention, showing a drive shaft, a partition member, a movable member and a control pressure chamber;

FIG. 13 is an enlarged fragmentary cross-sectional view of the compressor of FIG. 12, showing a clearance between the partition member and the movable member when the inclination angle is large;

FIG. 14 is an enlarged fragmentary cross-sectional view of the compressor of FIG. 12, showing a clearance between the partition member and the movable member when the inclination angle is small;

FIG. 15 is an enlarged fragmentary cross-sectional view of a compressor according to a fifth embodiment of the present invention, showing a drive shaft, a partition member, a movable member and a control pressure chamber; and

FIG. 16 is an enlarged fragmentary cross-sectional view of a compressor according to a sixth embodiment of the present invention, showing a drive shaft, a partition member, a movable member and a control pressure chamber.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following will describe a variable displacement type swash plate compressor (hereinafter simply referred to as compressor) according to various embodiments of the present invention with reference to the accompanying drawings. The compressor of the embodiments is mounted on a vehicle and forms a part of a refrigeration circuit of a vehicle air conditioner.

Referring to FIGS. 1 and 2, there is shown a compressor according to a first embodiment of the present invention. The compressor includes a housing 1, a drive shaft 3, a swash plate 5, a link mechanism 7, a plurality of pistons 9, a plurality of pairs of shoes 11 a, 11 b and an actuator 13. As shown in FIG. 3, the compressor further includes a control mechanism 15.

As shown in FIGS. 1 and 2, the housing 1 includes a front housing member 17, a rear housing member 19, a first cylinder block 21, a second cylinder clock 23, a first valve forming plate 39 and a second valve forming plate 41. In the compressor according to the present embodiment, the sides of the compressor where the front housing member 17 and the rear housing member 19 are positioned correspond to the front and the rear of the compressor, respectively. In addition, the top and the bottom of the illustration of FIGS. 1 and 2 will be referred to the top and the bottom of the compressor. It is to be noted that the front and the rear of the compressor may be changed in accordance with the mounting of the compressor in the vehicle.

The front housing member 17 is formed with a boss 17 a projecting frontward and having therein a shaft seal device 25. A first suction chamber 27 a and a first discharge chamber 29 a are formed in the front housing member 17. The first suction chamber 27 a has an annular shape and is positioned on the radially inner side of the front housing member 17. The first discharge chamber 29 a has also an annular shape and is disposed radially outward of the first suction housing 27 a.

A part of the aforementioned control mechanism 15 is formed in the rear housing member 19. The rear housing member 19 has therein a second suction chamber 27 b and a second discharge chamber 29 b and a pressure control chamber 31. The pressure control chamber 31 is positioned in the center of the rear housing member 19. The second suction chamber 27 b has an annular shape and is positioned radially outward of the pressure control chamber 31. The second discharge chamber 29 b has also an annular shape and is disposed radially outward of the second suction chamber 27 b. The first discharge chamber 29 a and the second discharge chamber 29 b are connected to each other through a discharge passage (not shown). The discharge passage is connected to a discharge port (not shown).

The first cylinder block 21 is disposed between the front housing member 17 and the second cylinder block 23. The first cylinder block 21 has therein a plurality of first cylinder bores 21 a extending in the direction of the axis O of the drive shaft 3. The first cylinder bores 21 a are spaced angularly at a regular interval in the circumferential direction of the cylinder block 21.

The first cylinder block 21 has therein a first shaft hole 21 b through which the drive shaft 3 is inserted. A first slide bearing 22 a is provided in the first shaft hole 21 b to support the drive shaft. Additionally, the first cylinder block 21 further has therein a first recess 21 c that is connected to the rear end of the first shaft hole 21 b. The first recess 21 c and the first shaft hole 21 b are formed coaxially. The first recess 21 c has a diameter greater than that of the first shaft hole 21 b. A first thrust bearing 35 a is mounted in the first recess 21 c. The first cylinder block 21 has therein a first communication passage 37 a extending in the axial direction.

The second cylinder block 23 is disposed between the first cylinder block 21 and the rear housing member 19. With the second cylinder block 23 and the first cylinder block 21 connected together, a swash plate chamber 33 is formed therebetween. The swash plate chamber 33 is connected to the first recess 21 c so that the first recess 21 c forms a part of the swash plate chamber 33. The swash plate chamber 33 is connected to the first communication passage 37 a.

The second cylinder block 23 has therein a plurality of second cylinder bores 23 a extending in the direction of the axis O of the drive shaft 3 and having substantially the same diameter as the first cylinder bores 21 a. The second cylinder bores 23 a are spaced angularly at a regular interval. Each second cylinder bore 23 a is paired and disposed coaxially with its corresponding first cylinder bore 21 a. According to the present invention, any number of the first and second cylinder bores 21 a, 23 a may be formed in the housing as long as the first and second cylinder bores 21 a. 23 a are provided in pairs. The first cylinder bores 21 a may have a diameter different from that of the second cylinder bores 23 a. The paired first and second cylinder bores 21 a, 23 a need not necessarily be coaxially disposed.

The second cylinder block 23 has therein a second shaft hole 23 b through which the drive shaft 3 is inserted. A second slide bearing 22 b is provided in the second shaft hole 23 b to support the drive shaft 3. It is to be noted that the first and second slide bearings 22 a, 22 b may be replaced with ball bearings.

A second recess 23 c is formed in the second cylinder block 23 and connected to the front end of the second shaft hole 23 b. The second recess 23 c is disposed coaxially with the second shaft hole 23 b. The second recess 23 c is formed with a diameter greater than that of the second shaft hole 23 b. The second recess 23 c is connected to the swash plate chamber 33 so as to form a part of the swash plate chamber 33. A second thrust bearing 35 b is mounted in the second recess 23 c.

The second cylinder block 23 has a suction port 330 and a second communication passage 37 b. The swash plate chamber 33 is connected through the suction port 330 to an evaporator (not shown) that is connected in the refrigeration circuit of the air compressor. The second communication passage 37 b extends in the front-rear direction and communicates with the swash plate chamber 33.

The first housing 17 and the first cylinder block 21 are joined together with the first valve forming plate 39 interposed therebetween.

The first valve forming plate 39 has therethough a first suction hole 390 a and a first discharge hole 390 b for each first cylinder bore 21 a and a first suction communication hole 390 c. Each first cylinder bore 21 a is communicable with the first suction chamber 27 a via the first suction hole 390 a and also with the first discharge chamber 29 a via the first discharge hole 390 b. The first suction chamber 27 a and the first communication passage 37 a are in communication with each other through the first suction communication hole 390 c.

The rear housing member 19 and the second cylinder block 23 are joined together with the second valve forming plate 39 interposed therebetween.

The second valve forming plate 41 has therethough a second suction hole 410 a and a second discharge hole 410 b for each second cylinder bore 23 a and a second suction communication hole 410 c. Each second cylinder bore 23 a is communicable with the second suction chamber 27 b via the second suction hole 410 a and also with the second discharge chamber 29 b via the second discharge hole 410 b. The second suction chamber 29 a and the second communication passage 37 b are in communication with each other through the second suction communication hole 410 c.

Although not illustrated in the drawing, the first valve forming plate 39 has a plurality of first suction reed valves that open and close the respective first suction holes 390 a, a plurality of discharge reed valve that opens and closes the respective second discharge holes 390 b, and a retainer plate that restricts the opening of each discharge reed valve. In addition, the second valve forming plate 41 has a plurality of second suction reed valves that open and close the respective second suction holes 410 a, a plurality of discharge reed valves that open and close the respective second discharge holes 410 b, and a retainer plate that restricts the opening of each discharge reed valve. The first and second cylinder blocks 21, 23 are formed with a retainer recess that restricts the opening of each suction reed valve.

The first and second suction chambers 27 a, 27 b communicates with the swash plate chamber 33 through the first and second communication passages 37 a, 37 b and the first and second suction communication passages 390 c, 410 c, respectively, so that pressures in the first and second suction chambers 27 a, 27 b are substantially the same as that in the swash plate chamber 33. Since low-pressured refrigerant gas having passed through the evaporator is flowed into the swash plate chamber 33 through the suction port 330, the pressures in the swash plate chamber 33 as well as the first and second suction chambers 27 a, 27 b are lower than those in the first and second discharge chambers 29 a, 29 b.

The drive shaft 3 includes a drive shaft body 30, a first support member 43 a and a second support member 43 b. The drive shaft 3 has at the front end thereof a threaded portion 3 a. The drive shaft 3 is connected to a pulley or an electromagnetic clutch (neither shown) through the threaded portion 3 a. Additionally, the drive shaft 3 has therein an axial passage 3 b and a radial passage 3 c, which will be described later.

The drive shaft body 30 extends axially in the housing 1. The drive shaft body 30 has at the front end thereof a first small diameter portion 30 a and at the rear end thereof a second small diameter portion 30 b.

The drive shaft body 30 has mounted thereon the swash plate 5, the link mechanism 7 and the actuator 13 that are disposed in the swash plate chamber 33. The swash plate 5 is mounted on the drive shaft 3 for rotation therewith in the swash plate chamber 33.

The first support member 43 a has a generally cylindrical shape extending along the axis O of the drive shaft 3. The first support member 43 a is press fitted on the first small diameter portion 30 a of the drive shaft body 30. The first support member 43 a has a first flange 430 and a mounting portion (not shown) through which a second pin 47 b, which will be described later, is inserted.

A return spring 44 a is mounted around the first support member 43 a. The return spring 44 a extends in the direction the axis O between the first flange 430 and the swash plate 5.

The second support member 43B has a generally cylindrical shape extending along the axis O of the drive shaft 3. The second support member 43 b is press fitted on the rear end of the second small diameter portion 30 a of the drive shaft body 30. The second support member 43 b has at the front thereof a second flange 431. The second support member 43 b further has a first seal ring 46 a and a second seal ring 46 b disposed rearward of the second flange 431.

The drive shaft 3 extends through the shaft seal device 25, the first suction chamber 27 a, the first and second shaft holes 21 b, 23 b, the first and second thrust bearings 35 a, 35 b, the swash plate chamber 33 and the pressure control chamber 31 in the housing 1, so that the drive shaft 3 is supported rotatably about the axis O extending in the front-rear direction of the compressor in the housing 1. With the drive shaft 3 thus supported by the housing 1, the first thrust bearing 35 a is held axially between the first flange 430 of the first support member 43 a and the front surface of the first recess 21 c. The first and second seal rings 46 a, 46 b are disposed in the second shaft hole 23 b so as to seal between the pressure control chamber 31 and the swash plate chamber 33.

The swash plate 5 has a generally disk shape having a front surface 5 a and a rear surface 5 b. The swash plate 5 is disposed in the swash plate chamber 33 with the front surface 5 a and the rear surface 5 b thereof facing frontward and rearward of the compressor, respectively. In other words, the front surface 5 a faces the front housing member 17 and the rear surface 5 b faces the rear housing member 19.

The swash plate 5 includes a ring plate 45 that has a shape of a circular disk having at the center thereof a hole 45 a. The swash plate 5 is mounted on the drive shaft 3 with the drive shaft body 30 inserted through the hole 45 a of the ring plate 45 of the swash plate 5 in the swash plate chamber 33. The ring plate 45 further has therethrough a hole 45. The ring plate 45 further has a connecting portion 45 c projecting rearward from the rear surface 5 b of the swash plate 5. The connecting portion 45 c is disposed opposite from the hole 45 b with respect to the axis O.

The link mechanism 7 includes a lug arm 49. The lug arm 49 is disposed frontward of the swash plate 5 in the swash plate chamber 33 and positioned between the swash plate 5 and the first support member 43 a. The lug arm 49 has a generally L-shape and has at the rear end thereof a weight 49 a. The weight 49 a may be designed in any suitable shape.

The lug arm 49 is connected at the rear end thereof to the ring plate 45 via a first pin 47 a. Thus, the lug arm 49 is supported swingably about a first axis M1 corresponding to the axis of the first pin 47 a and relative to the ring plate 45, or to the swash plate 5.

The front end of the lug arm 49 is connected to the first support member 43 a by a second pin 47 b in such a way that the lug arm 49 is supported swingably about a second axis M2 corresponding to the axis of the second pin 47 b and relative to the first support member 43 a, or to the drive shaft 3. The lug arm 49, the first and second pins 47 a, 47 b, a pair of connecting arms 132 and a third pin 47 c, which will be described later, cooperate to form the link mechanism 7 according to the present invention.

The weight 49 a is provided on the rear side of the lug arm 49, that is, on the side of the lug arm 49 that is opposite from the second axis M2 with respect to the first axis M1. With the lug arm 49 supported by the ring plate 45 at the first pin 47 a, the weight 49 a is located on the rear side of the ring plate 45, that is, on the rear side of the rear surface 5 b of the swash plate 5. The centrifugal force caused by the rotation of the swash plate 5 about the axis O of the drive shaft 3 acts on the weight 49 a on the rear surface 5 b of the swash plate 5.

The swash plate 5 is connected to the drive shaft 3 via the link mechanism 7, so that the swash plate 5 is rotatable with the drive shaft 3. With the swinging movement of the opposite ends of the lug arm 49 about the first axis M1 and the second axis M2, the inclination angle of the swash plate 5 with respect to an imaginary plane extending perpendicularly to the axis O is variable between the maximum inclination angle position shown in FIGS. 1 and the minimum inclination angle position shown in FIGS. 2. In other words, the link mechanism 7 permits changing of the inclination angle of the swash plate 5 with respect to the imaginary plane extending perpendicular to the direction of the axis O of the drive shaft 3.

The piston 9 is a double-headed piston having at the front end thereof a first head portion 9 a and at the rear end thereof a second head portion 9 b, respectively, as shown in FIGS. 1 and 2. The first head portion 9 a is reciprocally movably received in the first cylinder bore 21 a and a first compression chamber 53 a is defined by the first head portion 9 a and the first valve forming plate 39 in the first cylinder bore 21 a. The second head portion 9 b is reciprocally movably received in the second cylinder bore 23 a and a second compression chamber 53 b is defined by the second head portion 9 b and the second valve forming plate 41 in the second cylinder bore 23 a.

Each piston 9 has therein at the center thereof a piston recess 9 c to receive therein a pair of hemispherical shoes 11 a, 11 b. The rotation of the swash plate 5 is converted to the reciprocal movement of the piston 9 by way of the shoes 11 a, 11 b. The shoes 11 a, 11 b correspond to the conversion mechanism of the present invention. Thus, the first head portion 9 a and the second head portion 9 b of the piston 9 are reciprocally movable in the first cylinder bore 21 a and the second cylinder bore 23 a, respectively, with a stroke length that is determined by the inclination angle of the swash plate 5.

The top dead center positions of the first head portion 9 a and the second head portion 9 b are variable with the change of the stroke length that is caused by the change of the inclination angle of the swash plate 5. Specifically, the top dead center of the second head portion 9 b moves a longer distance than the first head portion 9 a as the inclination angle of the swash plate 5 is reduced, as shown in FIG. 1.

The actuator 13 is disposed rearward of the swash plate 5 in the swash plate chamber 33. Specifically, the actuator 13 is disposed in the region of the swash plate chamber 33 corresponding to the second cylinder block 23 so that the actuator 13 is movable into the second recess 23 c.

As shown in FIG. 4, the actuator 13 has a movable member 13 a, a partition member 13 b and a control pressure chamber 13 c. The control pressure chamber 13 c is formed between the movable member 13 a and the partition member 13 b.

The movable member 13 a includes a bottom wall 130, a peripheral wall 131, the aforementioned paired arms 132 (only one arm being shown in FIG. 1) and an elastically deformable O-ring 51 a. The O-ring 51 a corresponds to the second seal member of the present invention.

As shown in FIG. 4, the bottom wall 130 forms the rear part of the movable member 13 a, extending outwardly in the radial direction of the axis O. The bottom wall 130 has therethrough a hole 130 a. The bottom wall 130 further has a first groove 130 b recessed from the circular inner surface forming the hole 130 a of the bottom wall 130. The O-ring 51 a is disposed in the first groove 130 b, so that the O-ring 51 a is disposed between the drive shaft 3 and the movable member 13 a. The peripheral wall 131 extends frontward from the outer periphery of the bottom wall 130. The movable member 13 a has a bottomed cylindrical shape formed by the bottom wall 130 and the peripheral wall 131. Each arm 132 has an insertion hole 132 a into which a third pin 47 c, which will be described later, is inserted.

The partition member 13 b has a disk shape having an outer diameter that is greater than the drive shaft body 30 and substantially the same as the first inner diameter L1 of the movable member 13 a. The partition member 13 b is provided with an elastically deformable O-ring 51 b. The O-ring 51 b corresponds to the first seal member according to the present invention. The O-rings 51 a, 51 b for first and second seal members may be substituted by X-rings.

The partition member 13 b has at the center thereof a hole 133. The partition member 13 b has an outer peripheral surface 134 in which a second groove 134 a is formed. The O-ring 51 b is disposed in the second groove 134 a, so that the O-ring 51 b is disposed between the partition member 13 b and the movable member 13 a. As has been described, the partition member 13 b has a diameter that is greater than the drive shaft body 30, so that the diameter of the O-ring 51 b is greater than that of the O-ring 51 a.

The second small diameter portion 30 b of the drive shaft body 30 is inserted through the insertion hole 130 a of the movable member 13 a so that the movable member 13 a is slidable along the second small diameter portion 30 b in the direction of the axis O. The movable member 13 a is mounted on the drive shaft 3 for rotation therewith in the swash plate chamber 33. The second small diameter portion 30 b is press fitted in the hole 133 of the partition member 13 b. Thus, the partition member 13 b is fixedly mounted on the second small diameter portion 30 b of the drive shaft body 30 for rotation therewith. The partition member 13 b may be mounted slidably on the second small diameter portion 30 b along the direction of the axis O.

The partition member 13 b fixed on the second small diameter portion 30 b is disposed in the movable member 13 a and circumferentially surrounded by the peripheral wall 131 of the movable member 13 a. As the movable member 13 a moves along the axis O, the inner peripheral surface 131 a of the peripheral wall 131 slides along the outer peripheral surface 134 of the partition member 13 b.

With the partition member 13 b surrounded by the peripheral wall 131, the control pressure chamber 13 c is formed between the movable member 13 a and the partition member 13 b. The control pressure chamber 13 c is defined in the swash plate chamber 33 by the bottom wall 130 and the peripheral wall 131 of the movable member 13 a, the partition member 13 b, and the outer peripheral surface 300 of the drive shaft 3.

With the second small diameter portion 30 b inserted through the movable member 13 a, the O-ring 51 a is positioned and elastically deformed between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a, thus providing sealing between the control pressure chamber 13 c and the swash plate chamber 33. With the partition member 13 b surrounded by the peripheral wall 131 of the movable member 13 a, the O-ring 51 b is positioned between the partition member 13 b and the movable member 13 a. The O-ring 51 b is elastically deformed between the outer peripheral surface 134 of the partition member 13 b and the inner peripheral surface 131 a of the peripheral wall 131 of the movable member 13 a, thus providing sealing between the control pressure chamber 13 c and the swash plate chamber 33. Accordingly, the O-rings 51 a, 51 b secures sealing between the control pressure chamber 13 c and the swash plate chamber 33.

Referring to FIG. 4, X1 indicates a first slide area of the inner peripheral surface 131 a of the movable member 13 a with which the O-ring 51 b in the second annular groove 134 a formed in the outer peripheral surface 134 of the partition member 13 b is in sliding contact when the movable member 13 a slides on the second small diameter portion 30 b of the movable member 13 a along the axis O of the drive shaft 3. In addition, X2 indicates a second slide area of the outer peripheral surface 300 of the second small diameter portion 30 b with which the O-ring 51 a mounted in the movable member 13 a is in sliding contact.

The inner peripheral surface 131 a of the peripheral wall 131 has a sloped portion 135 which forms part of the first slide area X1. The diameter of the sloped portion 135 is increased linearly rearwardly of the peripheral wall 130. As shown in FIG. 4, the movable member 13 a has a first inner diameter L1 in the region frontward of the sloped portion 135 and a second inner diameter L2 in the region rearward of the sloped portion 135 that is greater than the first inner diameter L1.

When the movable member 13 a slides rearward on the second small diameter portion 30 b of the drive shaft body 30 along the axis O to a position where the partition member 13 b is located frontward of the sloped portion 135 in the first slide area X1, as shown in FIG. 5, a first clearance S1 is formed between the outer peripheral surface 134 of the partition member 13 b and the inner peripheral surface 131 a of the peripheral wall 131. When the movable member 13 a slides rearward on the second small diameter portion 30 b of the drive shaft body 30 along the axis O to a position where the partition member 13 b is located rearward of the sloped portion 135 in the first slide area X1, as shown in FIG. 6, a second clearance S2 that is greater than the first clearance S1 is formed between the outer peripheral surface 134 of the partition member 13 b and the inner peripheral surface 131 a of the peripheral wall 131. In this actuator 13, the clearance between the outer peripheral surface 134 of the partition member 13 b and the inner peripheral surface 131 a of the peripheral wall 131 of the movable member 13 a is gradually increased from S1 to S2 in the first slide area X1 with the movement of the movable member 13 a relative to the partition member 13 b. In other words, the clearance between the partition member 13 b and the movable member 13 a when the swash plate 5 is at its minimum inclination angle position is greater than the clearance between the partition member 13 b and the movable member 13 a when the swash plate 5 is at its maximum inclination angle position The clearance between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a remains constant irrespective of the movement of the movable member 13 a along the second slide area X2. It is to be noted that the first clearance S1 and the second clearance S2 are shown in an exaggerated manner in FIGS. 5 and 6.

As shown in FIGS. 1 and 2, the connecting arms 132 of the movable member 13 a are connected to the connecting portion 45 c of the ring plate 45 by the third pin 47 c, so that the swash plate 5 is supported swingably about the axis M3 of the third pin 47 c by the movable member 13 a. The first pin 47 a and the third pin 47 c are disposed on radially opposite sides of the drive shaft body 30. In other words, the arms 132 are connected to the ring plate 45 at positions that are radially opposite sides of the hole 45 b with respect to the axis O.

An inclination angle reducing spring 44 b is interposed between the partition member 13 b and the ring plate 45. Specifically, the rear end of the inclination angle reducing spring 44 b is mounted with the rear end thereof placed in contact with the partition member 13 b and the front end thereof placed in contact with the ring plate 45, respectively. The inclination angle reducing spring 44 b urges the partition member 13 b and the ring plate 45 away from each other.

The axial passage 3 b is formed in the second small diameter portion 30 b of the drive shaft body 30, extending in the direction of the axis O. The rear end of the axial passage 3 b is opened at the rear end surface of the second small diameter portion 30 b so as to communicate with the pressure control chamber 31. The radial passage 3 c is connected to the front end of the axial passage 3 b and extends radially in the second small diameter portion 30 b. With the actuator 13 mounted on the drive shaft body 30, the radial passage 3 c is opened to the control pressure chamber 13 c. Consequently, the pressure control chamber 31 and the control pressure chamber 13 c are in communication with each other through the axial passage 3 b and the radial passage 3 c.

As shown in FIG. 3, the control mechanism 15 includes a bleeding passage 15 a, a feeding passage 15 b, a control valve 15 c, an orifice 15 d, the axial passage 3 b and the radial passage 3 c.

The bleeding passage 15 a is connected at the one end thereof to the pressure control chamber 31 and at the other end thereof to the second suction chamber 27 b, so that the control pressure chamber 13 c, the pressure control chamber 31 and the second suction chamber 27 b are connected to one another through the bleeding passage 15 a, the axial passage 3 b and the radial passage 3 c. The feeding passage 15 b is connected at the one end thereof to the pressure control chamber 31 and at the other end thereof to the second discharge chamber 29 b. Thus, the control pressure chamber 13 c, the pressure control chamber 31 and the second discharge chamber 29 b are connected to one another through the feeding passage 15 b, the axial passage 3 b and the radial passage 3 c. The orifice 15 d is provided in the feeding passage 15 b.

The control valve 15 c is provided in the bleeding passage 15 a and controls the opening of the bleeding passage 15 a in response to the pressure in the second suction chamber 27 b.

The compressor has a pipe for connection between the suction port 330 and the evaporator (not shown) and a pipe for connection between the discharge port and the condenser (not shown). The condenser is connected to the evaporator via pipes and the expansion valve. The compressor, the evaporator, the expansion valve and the condenser cooperate to form a refrigeration circuit of a vehicle air conditioner. The evaporator, the expansion valve, the condenser and the pipes are omitted from the illustration in the drawings.

In the above-described compressor, the rotation of the swash plate 5 driven by the drive shaft 3 causes the first and second head portions 9 a, 9 b of each piston 9 to reciprocate in their corresponding first and second cylinder bores 21 a, 23 a, respectively. Accordingly, the volume of the first and second compression chambers 53 a, 53 b is changed for compression of refrigerant gas with the stroke length of the piston 9. In accordance with the reciprocating movement of each piston 9, suction phase in which the refrigerant gas is introduced into the first and second compression chamber 53 a, 53 b, compression phase in which refrigeration gas is compressed in the first and second compression chambers 53 a, 53 b, and discharge phase in which the compressed refrigerant gas is discharged out from the first and second compression chambers 53 a, 53 b, take place repeatedly. The refrigerant gas discharged into the first and second discharge chambers 29 a, 29 b passes through the discharge passage and is discharged to the condenser through the discharge port.

In the suction phase, the piston compression force acts on the rotary assembly, which is formed by the swash plate 5, the ring plate 45, the lug arm 49 and the first pin 47 a, in the direction that reduces the inclination angle of the swash plate 5. By changing the inclination angle of the swash plate 5, the stroke length of the piston 9 is changed and, accordingly, the displacement of the compressor is varied.

In the control mechanism 15 shown in FIG. 3, when the opening of the bleeding passage 15 a is increased by the control valve 15 c, the pressures in the pressure control chamber 31 and the control pressure chamber 13 c become substantially the same as the pressure in the second suction chamber 27 b, so that the variable pressure difference between the control pressure chamber 13 c and the swash plate chamber 33 becomes small. Accordingly, the pressure P1 in the control pressure chamber 13 c (FIGS. 8 and 9) acting on the movable member 13 a in the actuator 13 is decreased. The piston compression force acting on the swash plate 5 causes the movable member 13 a to slide frontward along the second small diameter portion 30 b of the drive shaft body 30.

In this compressor, compression reaction force acting on the swash plate 5 through the piston 9 urges the swash plate 5 in the direction that reduces its inclination angle. The above compression reaction force corresponds to the resultant force of the compression reaction forces of the respective pistons acting on the swash plate 5. The movable member 13 a is pulled by the swash plate 5 through the arms 132 and the connecting portion 45 c thereby to move frontward along the axis O in the swash plate chamber 33 until the ring plate 45 of the swash plate 5 is set in contact with the rear end of the return spring 44 a. Thus, the swash plate 5 is set in contact with the rear end of the return spring 44 a. With the frontward movement of the movable member 13 a in the swash plate chamber 33, the swash plate 5 swings about the third axis M3 against the urging force of the return spring 44 a. In addition, the rear end of the lug arm 49 swings about the first axis M1 and the front end of the lug arm 49 swings about the second axis M2, so that the front end of the lug arm 49 moves towards the first flange 430 of the support member 43 a. As a result, the swash plate 5 swings about the first axis M1 with the third axis M3 as the point of application. The inclination angle of the swash plate 5 with respect to an imaginary plane extending perpendicularly to the axis O of the drive shaft is reduced, so that the stroke length of each piston 9 is reduced. Accordingly, the discharge volume per rotation of the drive shaft 3 and hence the displacement of the compressor is reduced.

The centrifugal force generated by the rotation of the weight 49 a is also applied to the swash plate 5, so that the swash plate 5 tends to be easily tilted in the direction that reduces its inclination angle.

When the stroke length of the piston 9 is reduced with a reduction of the inclination angle of the swash plate 5, the top dead center of the second head portion 9 b is shifted away from the second valve forming plate 41. When the inclination angle of the swash plate 5 is reduced close to zero, slight compression takes place in the first compression chamber 53 a with the discharge reed valve slightly opened by refrigerant gas whereas no compression takes place in the second compression chamber 53 b and its associated discharge reed valve remains closed accordingly.

The frontward sliding movement of the movable member 13 a along the second small diameter portion 30 b in response to a reduction of the pressure P1 in the control pressure chamber 13 c acting on the movable member 13 a that is due to a reduced pressure in the pressure control chamber 31 causes relative movement of the partition member 13 b rearward in the first slide area X1 along the inner peripheral surface 131 a of the peripheral wall 131. When the swash plate 5 is at its minimum inclination angle position, the partition member 13 b is positioned rearward of the sloped portion 135 in the first slide area X1, as shown in FIG. 6. Then, the movable member 13 a is positioned in the front area of the second slide area X2.

In the control mechanism 15 shown in FIG. 3, when the opening of the bleeding passage 15 a is reduced by the control valve 15 c, the pressure in the pressure control chamber 31 is increased by the pressure of refrigerant gas in the second discharge chamber 29 b and the pressure in the control pressure chamber 13 c is increased, accordingly. The variable pressure difference between the control pressure chamber 13 c and the swash plate chamber 33 becomes large, so that the pressure P1 in the control pressure chamber 13 c acting on the movable member 13 a is increased. The movable member 13 a moves rearward along the second small diameter portion 30 b against the piston compression force acting on the swash plate 5 from the position shown in FIG. 1 to the position in the second recess 23 c shown in FIG. 2. The control mechanism 15 controls the pressure in the control pressure chamber 13 c.

The swash plate 5 is pulled rearward by the movable member 13 a through the arms 132 and the connecting portion 45 c against the urging force of the inclination angle reducing spring 44 b. Accordingly, the swash plate 5 swings about the third axis M3 in the direction that increases its inclination angle 5. The rear end of the lug arm 49 swings about the first axis M1 and the front end of the lug arm 49 swings about the second axis M2 in the direction that increases the inclination angle of the swash plate 5, so that the front end of the lug arm 49 moves rearward away from the first flange 430 of the first support member 43 a. As a result, the swash plate 5 swings about the first axis M1 with the third axis M3 as the point of application in the direction that is reverse to the direction that reduces the inclination angle of the swash plate 5. In other words, the control pressure chamber 13 c moves the movable member 13 a in a direction that increases the inclination angle with an increase of the pressure in the control pressure chamber 13 c. The inclination angle of the swash plate 5 is thus increased and the stroke length of each piston 9 is increased. Accordingly, the discharge volume per rotation of the drive shaft 3 and hence the displacement of the compressor is increased. The movable member 13 a is movable in the direction of the axis O on the drive shaft 3 and the partition member 13 b to change the inclination angle of the swash plate 5.

The rearward movement of the movable member 13 a along the second small diameter portion 30 b by the increased pressure P1 in the control pressure chamber 13 c causes frontward movement of the partition member 13 b relative to the movable member 13 a in the first slide area X1. When the inclination angle of the swash plate 5 becomes maximum, the partition member 13 b is positioned frontward of the sloped portion 135 in the first slide area X1, as shown in FIG. 5, meanwhile the movable member 13 a is positioned in the rear part of the second slide area X2.

In changing the displacement of the compressor by changing the inclination angle of the swash plate 5, the movable member 13 a of the actuator 13 moves slidably on the second small diameter portion 30 b of the drive shaft body 30 along the axis O. With the slidable movement of the movable member 13 a, the O-rings 51 a, 51 b are elastically deformed between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a and between the partition member 13 b and the inner peripheral surface 131 a of the peripheral wall 131, respectively, which causes resistance against the sliding movement the movable member 13 a along the axis O. In increasing the displacement of the compressor by increasing the inclination angle of the swash plate 5, the movable member 13 a needs to slide against the resistance caused by the O-rings 51 a, 51 b (hereinafter referred to as the slide resistance R3), so that the pressure P1 in the control pressure chamber 13 c acting on the movable member 13 a needs to be strong enough to overcome the slide resistance R3. In the compressor of the illustrated embodiment, the return spring 44 a urges the actuator 13 through the swash plate 5 in the direction that increases the inclination angle of the swash plate 5. As the inclination angle of the swash plate 5 is reduced with a decrease of the pressure in the control pressure chamber 13 c, the actuator 13 is urged by the return spring 44 a through the swash plate 5 in the direction that increases the inclination angle of the swash plate 5. The return spring 44 a ensures the movable member 13 a to move slidably in the direction that increases the inclination angle of the swash plate 5 against the slide resistance R3.

Referring to FIG. 7, there is shown a compressor according to an example for comparison with the compressor of the present embodiment in which no sloped portion such as 135 is formed in the inner peripheral surface 131 a of the peripheral wall 131. Specifically, the inner diameter of the movable member 13 a in the example remains constant at L1. As with the compressor of the first embodiment, the clearance formed between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a remains constant irrespective of the position of the movable member 13 a in the second slide area X2. The rest of the configuration of the compressor according to the comparison example is substantially the same as the compressor according to the first embodiment. Like parts or elements are designated by like reference numerals and the description thereof will not be reiterated.

In the compressor of the comparison example having such configuration, the first clearance S1 formed between the outer peripheral surface 134 of the partition member 13 b and the inner peripheral surface 131 a of the peripheral wall 131 remains constant irrespective of the position of the partition member 13 b relative to the movable member 13 a in the first slide area X1. In other words, the clearance formed between the outer peripheral surface 134 and the inner peripheral surface 131 a remains constant at the first clearance S1 when the swash plate 5 is at its maximum inclination angle position or at its minimum inclination angle position. In addition, the clearance formed between the second small diameter portion 30 b and the movable member 13 a remains constant irrespective of the change in the pressure P1 in the control chamber, or irrespective of the inclination angle of the swash plate 5.

Referring to FIGS. 8 and 9, R1 represents the sum of the resistance by elastic deformation of the O-ring 51 a that is determined by the clearance between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a and the resistance by elastic deformation of the O-ring 51 b that is determined by the clearance between the outer peripheral surface 134 of the partition member 13 b and the inner peripheral surface 131 a of the peripheral wall 131 of the movable member 13 a. The resistance R1 is variable in accordance with the clearance. R2 represents the sum of the resistances caused by elastic deformation of the O-rings 51 a, 51 b which is increased with an increase of the pressure P1 in the control pressure chamber. As indicated in the chart of FIG. 8, the slide resistance R3 is resultant force of the resistance R1 and the resistance R2. The pressure P1 in the control pressure chamber 13 c acting on the movable member 13 a is also shown in the charts of FIGS. 8 and 9.

In the compressor of the comparison example, the clearance between the outer peripheral surface 134 and the inner peripheral surface 131 a and the clearance between the second small diameter portion 30 b and the movable member 13 a remain constant, respectively, irrespective of the inclination angle of the swash plate 5. As indicated in FIG. 8, the resistance R1 remains constant irrespective of the pressure P1 in the control pressure chamber 13 c. An increase of the pressure P1 in the control pressure chamber 13 c increases the resistance R2. In the compressor of the comparison example, the slide resistance R3 increases from a point corresponding to the resistance R1 with an increase of the pressure P1 in the control pressure chamber 13 c. When the pressure P1 in the control pressure chamber 13 c acting on the movable member 13 a is small and the swash plate 5 is at its minimum inclination angle position, the slide resistance R3 becomes large relative to the pressure P1 in the control pressure chamber 13 c. In the compressor of the comparison example, therefore, the sliding movement of the movable member 13 a along axis O on the second small diameter portion 30 b becomes difficult when the pressure P1 in the control pressure chamber 13 c is reduced. This makes it difficult for the swash plate 5 to increase its inclination angle from its minimum angle position, which causes poor controlling of the displacement of the compressor.

According to the compressor of the first embodiment in which the sloped portion 135 is formed in the peripheral wall 131, the portion of the inner peripheral surface 131 a having the first inner diameter L1 is formed frontward of the sloped portion 135 and the portion having the second inner diameter L2 rearward of the sloped portion 135 in the movable member 13 a. Consequently, when the pressure P1 in the control pressure chamber 13 c is increase to position the partition member 13 b frontward of the sloped portion 135 in the first slide movement area X1, as shown in FIG. 5, the first clearance S1 is formed between the outer peripheral surface 134 and the inner peripheral surface 131 a, as with the comparison example of the compressor. When the pressure P1 in the control pressure chamber 13 c is reduced to position the partition member 13 b rearward of the sloped portion 135 in the first slide area X1, the second clearance S2 that is greater than the first clearance S1 is formed between the outer peripheral surface 134 and the inner peripheral surface 131 a, as shown in FIG. 6.

In the compressor of the first embodiment, the clearance between the outer peripheral surface 134 and the inner peripheral surface 131 a becomes the first clearance S1 at the maximum inclination angle of the swash plate 5 and the second clearance S2 at the minimum inclination angle of the swash plate 5, respectively. Meanwhile, the clearance between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a remains constant irrespective of the inclination angle of the swash plate 5 in the compressor of the first embodiment, as well as the compressor of the comparison example.

In the compressor of the first embodiment in which the clearance between the outer peripheral surface 134 and the inner peripheral surface 131 a is increased from the first clearance S1 to the second clearance S2, the elastic deformation of the O-ring 51 b is smaller when the pressure P1 in the control chamber is low than when the pressure P1 is high. When the pressure P1 in the control pressure chamber 13 c is low and the clearance between the outer peripheral surface 134 and the inner peripheral surface 131 a is large, the elastic deformation of the O-ring 51 b is smaller, so that the resistance R1 may be reduced. Although the slide resistance R3 is increased in accordance with an increase of the pressure P1 in the compressor of the first embodiment, the slide resistance R3 of the first embodiment is smaller than that of the compressor of the comparison example because the resistance R1 of the compressor of the first embodiment is smaller than that of the compressor of the comparison example.

In the compressor of the first embodiment, when the swash plate 5 is at its minimum inclination angle, or when the pressure P1 in the control pressure chamber 13 c acting on the movable member 13 a is small, the slide resistance R3 may be reduced to a relatively low level for the pressure P1 in the control pressure chamber 13 c. This allows the movable member 13 a to slide easily on the second small diameter portion 30 b along the axis O when the pressure in control pressure chamber 13 c is low. Accordingly, the compressor of the first embodiment permits increasing the inclination angle of the swash plate 5 from its minimum angle easily.

Therefore, the compressor of the first embodiment may achieve great controllability.

Furthermore, in the compressor of the present embodiment in which the inner peripheral surface 131 a of the peripheral wall 131 is formed with the sloped portion 135, the clearance only between the outer peripheral surface 134 of the partition member 13 b and the inner peripheral surface 131 a of the peripheral wall 131 is variable between from the first clearance S1 and the second clearance S2 with a change in the inclination angle of the swash plate 5. Thus, the production of the compressor may be simplified, as compared with the case of a compressor in which the actuator 13 is configured so that the clearance between the outer peripheral surface 300 of the second small diameter portion 30 b and the inner peripheral surface of the movable member 13 a, as well as the clearance between the outer peripheral surface 134 and the inner peripheral surface 131 a, are variable. In addition, in the compressor in which the partition member 13 b has a diameter greater than that of the drive shaft body 30 and is fixedly mounted on the second small diameter portion 30 b of the drive shaft body 30, the O-ring 51 b that is mounted in the partition member 13 b has a diameter greater than that of the O-ring 51 a which is set in sliding contact with the peripheral surface of the second small diameter portion 30 b of the drive shaft body 30. Such configuration permits effectively reducing the resistance R1 by reducing the elastic deformation of the O-ring 51 b when the pressure P1 in the control pressure chamber is reduced and the swash plate 5 is at its minimum inclination angle accordingly, as compared with a case in which elastic deformation of only the O-ring 51 a is reduced. Thus, the compressor of the present embodiment permits reducing the slide resistance R3 effectively when the pressure P1 in the control pressure chamber 13 c acting on the movable member 13 a is at a low level.

Referring to FIG. 10, there is shown a compressor according to a second embodiment of the present invention in which a sloped portion 136 is formed in the inner peripheral surface 131 a of the peripheral wall 131 of the actuator 13. As with the sloped portion 135 of the first embodiment, the sloped portion 136 also increases its diameter linearly toward the rear of the peripheral wall 131. In the compressor of the second embodiment, the sloped portion 136 is formed extending substantially over the entire length of first slide area X1. The rest of the configuration of the compressor according to the second embodiment is substantially the same as the first embodiment.

Referring to FIG. 11, there is shown a compressor according to a third embodiment in which a sloped portion 137 is formed in the inner peripheral surface 131 a of the peripheral wall 131 of the actuator 13. As with the first diameter increasing portion 135 of the first embodiment, the sloped portion 137 forms part of the first slide area X1, similarly to the sloped portion 135 of the first embodiment. Unlike the first and sloped portions 135, 136, the sloped portion 137 is formed with a curved convex surface. Though not shown in the drawing, the sloped 137 may be formed extending substantially over the entire length of the entire first slide area X1 may be formed by the sloped portion 137. The rest of the configuration of the compressor according to the third embodiment is substantially the same as the first embodiment.

The compressors of the second and third embodiments offer substantially the same effects as the first embodiment. Especially, in the compressor of the second embodiment in which the sloped portion 136 is formed extending substantially the entire length of the first slide area X1, the clearance between the outer peripheral surface 134 and the inner peripheral surface 131 a may be varied more precisely in the area between the first clearance S1 and the second clearance S2.

The following will describe a compressor according to a fourth embodiment of the present invention with reference to the FIG. 12. Unlike the first, second and third embodiments in which the first, second and sloped portions 135, 136, 137 are formed in the inner peripheral surface 131 a of the peripheral wall 131, respectively, the compressor of the fourth embodiment has a sloped portion 301 that is formed in the outer peripheral surface 300 of the second small diameter portion 30 b. The sloped portion 301 is formed to cover part of the second slide area X2. The sloped portion 301 increases its diameter linearly toward the rear end of the sloped portion 301. Part of the second small diameter portion 30 b disposed frontward of the fourth diameter expansion portion 301 is formed with an outer diameter L3 and part of the second small diameter portion 30 b disposed rearward of the sloped portion 301 is formed with an outer diameter L4 that is greater than the outer diameter L3.

As shown in FIG. 13, when the movable member 13 a is positioned rearward of the sloped portion 301 in the second slide area X2 with the sliding movement of the movable member 13 a on the second small diameter portion 30 b along the axis O, a third clearance S3 is formed between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a, which increases gradually to a fourth clearance S4 with the frontward movement of the movable member 13 a along the sloped portion 301 in the second the slide area X2. For the sake of the description, the third and fourth spaced distances S3, S4 are illustrated in an exaggerated manner in FIGS. 13 and 14.

Unlike the compressor of the first embodiment in which the sloped portion 135 is formed in the inner peripheral surface 131 a of the peripheral wall 131, no sloped portion such as 135 is formed in the inner peripheral surface 131 a of the peripheral wall 131 of the compressor of the fourth embodiment, so that the inner diameter of the movable member 13 a remains constant at the first inner diameter L1, as shown in FIG. 12. Accordingly, the clearance between outer peripheral surface 134 of the partition member 13 b and the inner peripheral surface 131 a of the peripheral wall 131 remains constant at the first clearance S1. The rest of the configuration of the compressor according to the fourth embodiment is substantially the same as the first embodiment.

In this compressor, an increase of the pressure P1 in the control pressure chamber 13 c moves the movable member 13 a to a position rearward of the sloped portion 301 in the second slide area X2 where the third clearance S3 is formed between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a when the swash plate 5 is at its maximum inclination angle. A reduction of the pressure P1 in the control pressure chamber 13 c moves the movable member 13 a to a position frontward of the sloped portion 301 in the second slide area X2 where the fourth clearance S4 is formed between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a when the swash plate 5 is at its minimum inclination angle.

In the structure in which the clearance between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a is variable between the third clearance distance S3 and the fourth clearance S4, smaller elastic deformation of the O-ring 51 b occurs when the pressure P1 in the control pressure chamber 13 c is reduced, as compared with elastic deformation of the O-ring 51 b when the pressure P1 in the control pressure chamber is increased. As with the compressor of the first embodiment, the compressor of the fourth embodiment permits reducing the slide resistance R3 relative to the pressure P1 in the control pressure chamber 13 c acting on the movable member 13 a when the swash plate 5 is at its minimum inclination angle, as with the compressor of the first embodiment. Accordingly, the compressor of the fourth embodiment also permits easily increasing the inclination angle of the swash plate 5 from its minimum angle. The rest of the configuration of the compressor according to the fourth embodiment is substantially the same as the first embodiment.

Referring to FIG. 15, there is shown a compressor according to a fifth embodiment in which a sloped portion 302 is formed in the outer peripheral surface 300 of the second small diameter portion 30 b of the drive shaft body 30. As with the sloped portion 301 of the fourth embodiment, the sloped portion 302 increases its diameter linearly toward the rear end of the sloped portion 302. The sloped portion 302 is formed extending the entire length of the second slide area X2. The rest of the configuration of the compressor of the fifth embodiment is substantially the same as the first and fourth embodiments.

Referring to FIG. 16, there is shown a compressor according to a sixth embodiment in which a sloped portion 303 is formed in the outer peripheral surface 300 of the second small diameter portion 30 b of the drive shaft body 302. As with the above-described sloped portion 301, the sloped portion 303 is formed so as to cover part of the second slide area X2. Unlike the sloped portions 301, 302, the sloped portion 303 is formed with a curved convex surface. The entire second slide area X2 may be formed by the sloped portion 303. The rest of the configuration of the compressor according to the sixth embodiment is substantially the same as the first and fourth embodiments.

The compressors of the fifth and sixth embodiments offer substantially the same effects as the first and fourth embodiments. Especially, in the compressor of the fifth embodiment in which the entire second slide area X2 is formed by the sloped portion 302, so that the clearance between the outer peripheral surface 300 of the second small diameter portion 30 b and the movable member 13 a may be varied more precisely between the third clearance S3 and the fourth clearance S4.

The present invention is not limited to the above-described first to sixth embodiments, but may be modified in various manners within the scope of the present invention, as exemplified below.

The compressor may have a configuration in which one of the first, second and third embodiments may be combined with one of the fourth, fifth and six embodiments. In this case, the elastic deformation of both of the O-rings 51 a, 51 b when the pressure P1 in the control pressure chamber is small may be reduced, which permits further reducing the slide resistance R3 for the pressure P1 in the control pressure chamber 13 c acting on the movable member 13 a when the swash plate 5 is at its minimum inclination angle.

The present invention is applicable to a single head piston type swash plate compressor with variable displacement capability.

The actuator 13 and the link mechanism 7 may be disposed frontward and rearward of the swash plate 5, respectively, in the swash plate chamber 33.

In the control mechanism 15, the control valve 15 c and the orifice 15 d may be disposed in the feeding passage 15 b and in the bleeding passage 15 a, respectively. In this case, the control valve 15 c controls the opening of the feeding passage 15 b. Because the pressure P1 in the control pressure chamber may be quickly increased by the pressure of the refrigerant gas in the second discharge chamber 29 b, the displacement of the compressor may be increased quickly.

The control valve 15 c may be replaced with a flow rate control valve that controls the opening the bleeding passage 15 a or the feeding passage 15 b. In this case, a first pressure monitoring point is set in the discharge pressure region in the refrigeration circuit and a second pressure monitoring point is set at a point that is downstream of the first pressure monitoring point with respect to the refrigerant gas flowing direction and where the pressure of the refrigerant gas is lower than the first pressure monitoring point. The flow rate control valve controls the opening of the bleeding passage 15 a or the feeding passage 15 b based on the pressure difference between the first pressure monitoring point and the second pressure monitoring point.

The compressor of the present embodiment is applicable to any type of air conditioner. 

What is claimed is:
 1. A variable displacement type swash plate compressor comprising: a housing having therein a swash plate chamber and a plurality of cylinder bores; a drive shaft rotatably supported in the housing; a swash plate mounted on the drive shaft for rotation therewith in the swash plate chamber; a link mechanism permitting changing of an inclination angle of the swash plate with respect to the an imaginary plane extending perpendicular to a direction of an axis of the drive shaft; a plurality of pistons received in the respective cylinder bores and connected to the swash plate, the pistons being reciprocally movable with the rotation of the drive shaft with a stroke length that is determined by the inclination angle of the swash plate; a partition member mounted on the drive shaft for rotation therewith in the swash plate chamber; a movable member mounted on the drive shaft for rotation therewith in the swash plate chamber, the movable member being movable in the direction of the axis along the drive shaft and the partition member to change the inclination angle; a control pressure chamber formed between the partition member and the movable member, the control pressure chamber moving the movable member in a direction that increases the inclination angle with an increase of a pressure in the control pressure chamber; and a control mechanism controlling the pressure in the control pressure chamber; wherein a first seal member is disoposed between the partition member and the movable member, and the first seal member is elastically deformed to provide sealing between the control pressure chamber and the swash plate chamber, wherein a second seal member is disposed the drive shaft and the movable member, and the second seal member is elastically deformed to provide sealing between the control pressure chamber and the swash plate chamber, and wherein a clearance formed between the partition member and the movable member when the swash plate is at a minimum inclination angle is greater than the clearance formed between the partition member and the movable member when the swash plate is at a maximum inclination angle and/or a clearance formed between the drive shaft and the movable member when the swash plate is at the minimum inclination angle is greater than the clearance formed between the drive shaft and the movable member when the swash plate is at the maximum inclination angle.
 2. The variable displacement type swash plate compressor according to claim 1, wherein only the clearance formed between the partition member and the movable member when the swash plate is at the minimum inclination angle is greater than the clearance formed between the partition member and the movable member when the swash plate is at the maximum inclination angle. 